While upgrading Exchange 2013 RTM to CU1, I was surprised to see that the setup picks up that the RSAT Clustering CmdInterface was not installed. I thought that was a prerequisite for 2013 RTM!
Microsoft has updated the Exchange Remote Connectivity Analyzer site with the option to analyze message headers.
Exchange Team has updated the 2013 Deployment Assistant with more scenarios.
Exchange Team has released Cumulative Update 1 for Exchange Server 2013 RTM.
How to enable the light version of OWA in Exchange 2013?
Microsoft has released one of the most useful tool for Exchange Architects, Jetstress for Exchange 2013.
Exchange Team has released the deployment assistant for 2013 to help admins get through the tasks required in deploying a 2013 platform.